DE19918510B4 - With a gaseous fuel powered, supercharged internal combustion engine - Google Patents

Abstract

With a gaseous one Fuel-powered, supercharged internal combustion engine (1), which several combustion chambers (7), at least one line (13) and at least one housing (2) to the feeder from charge air to the combustion chambers (7), wherein each combustion chamber (7) at least one inlet valve (6) and additionally to the at least one inlet valve (6) at least one with a gas supply line (4) connected gas supply valve (5) for feeding of gas is assigned to a respective intake passage (3), and wherein the at least one housing (2) or the at least one conduit (13) for supplying charge air through at least a fixed separating element (10) permanently in at least two chambers (2a, 2b) with associated inflow channels (11a, 11b) or in at least two lines (13a, 13b) is divided.

Description

The The invention relates to a gas fueled, supercharged internal combustion engine according to the preamble of claim 1 further defined Art.

Such Internal combustion engines, which are also referred to as gas engines and find their use especially in commercial vehicles are from the known in the general art. For a bigger performance to be able to reach they are in most cases equipped with an exhaust gas turbocharger and are then called supercharged internal combustion engines designated.

Most of time such internal combustion engines have a charge air housing, before in the charge air pipe, the mixture formation takes place by means of a gas supply device or a gas mixing device added gas with the charge air is mixed. Through the charging air housing and the adjoining inlet channels the generated homogeneous gas-air mixture the combustion chambers of the Internal combustion engine fed individually.

Internal combustion engines However, with this type of mixture formation have due to the relative long way, which the gas-air mixture from the gassing up to the combustion chambers travels, a relatively sluggish one Response. Another problem of today's internal combustion engines is the more or less uneven distribution of the gas-air mixture on the individual combustion chambers. This leads to an unfavorable Efficiency of the internal combustion engine, said at higher charge said Problem still increases. Due to the bad equal distribution of the Gas-air mixture on the combustion chambers also arise with respect to the the internal combustion engine ejected Emissions disadvantages, since the for the emissions and the efficiency relevant ignition time of the mixture in the respective combustion chamber only for all combustion chambers can be adjusted together and this always the ignitability the worst Combustion chamber considered must become.

From the DE 692 29 520 T2 For example, an internal combustion engine with multiple combustion chambers is known, which gaseous fuel is supplied via a carburetor and an intake system. Via a throttle valve, an additional chamber can be connected to the intake system, so that results in a better charging efficiency of the internal combustion engine at higher speeds. In this known internal combustion engine no gas supply valve is provided so that it is only partially comparable with the present internal combustion engine.

It Object of the present invention, one with a gaseous fuel operated, supercharged internal combustion engine to create which better response, better efficiency and a has lower pollutant emissions as previously known, operated with a gaseous fuel, charged internal combustion engines.

According to the invention this Object by the mentioned in the characterizing part of claim 1 Characteristics solved.

By the assignment of at least one gas supply valve to each one Inlet and thus to each combustion chamber of the internal combustion engine results in a separate Eingasung for each combustion chamber. This advantageously allows a more even distribution of the gas or fuel to the individual combustion chambers.

Of the Pollutant emissions and the efficiency of the present engine depend on Combustion air ratio and the ignition timing off which over the ignitability the gas-air mixture is a dependency have. For this reason is for each operating state of the internal combustion engine an optimal combustion air ratio in all combustion chambers desirable. By the inventive separator, which the housing or the lead to the feeder Charge air in at least two chambers with associated inflow channels or divided into at least two lines, the influence is the intake stroke of a combustion chamber through the other combustion chambers is minimized, what a uniform distribution the charge air on all combustion chambers leads, by the same combustion air conditions in all combustion chambers to realize.

For example, in an internal combustion engine having six combustion chambers, three combustion chambers which do not fire one after the other can be combined with a chamber for supplying the charge air, thereby minimizing mutual influence of the intake stroke of the individual combustion chambers by air currents and air turbulences. The time interval at which the gas-air mixture is ignited in two successive combustion chambers within a chamber can namely be set so that it is greater than the respective opening period of the intake valves of the individual combustion chambers. As a result, the gas-air mixture located in an inlet channel can only reach the respectively provided combustion chamber. Thus, the supply of the same amount of gas and air is given to each combustion chamber, which is a very good Ver ensures combustion.

By the short ways, which the gas from the place of its gassing up to cover the combustion chambers must, results in a faster response and thereby a better dynamics of the internal combustion engine.

advantageous Refinements and developments of the invention will become apparent the dependent claims as well as from the below in principle with reference to the drawing Embodiments.

It shows:

1 a plan view of an internal combustion engine according to the invention;

2 a schematically illustrated plan view of an alternative embodiment of the internal combustion engine according to the invention;

3 a section along the line III-III 1 ; and

4 a sectional view analogous to 3 with an alternative arrangement of the gas supply valve.

In 1 is a six-cylinder internal combustion engine in a plan view 1 shown, which is operated with a gaseous fuel. The intended for commercial vehicles, but theoretically also used in passenger vehicles internal combustion engine 1 is charged by an exhaust gas turbocharger, not shown, and has for this purpose a housing 2 for supplying charge air in intake ducts 3 on, which in the following as charge air housing 2 referred to as. The inlet channels 3 are in 3 and 4 shown. The gas may be, for example, natural gas or LPG. At the internal combustion engine 1 is further a gas supply line 4 for supplying gas to gas supply valves 5 arranged.

The gas supply line 4 runs over the entire length of the internal combustion engine 1 and is with every gas supply valve 5 connected. The gas is recooled while relaxing and becomes the internal combustion engine 1 fed with a relatively low temperature, resulting in a lower mixture temperature and thus to a higher ren efficiency of the internal combustion engine 1 leads. This is reflected, for example, in the fact that an earlier ignition point can be selected for the same NO _x emissions.

The arrangement of gas supply valves 5 is in 3 and 4 better recognizable, whereby the variants by the functioning of the Gaszuführventile 5 differ. In the execution according to 3 gives each gas supply valve 5 from the gas supply line 4 extracted gas taking advantage of the pulse of the expanded gas directly into the respective inlet channel 3 from, which to a known inlet valve 6 and in the open position of the intake valve 6 in a combustion chamber 7 leads. The combustion chamber 7 is located in a known manner below a cylinder head 8th the internal combustion engine 1 in which the inlet valve 6 or several inlet valves 6 are arranged. Alternatively, it would also be possible to use the gas supply valves 5 in the cylinder head 8th to arrange.

In the execution according to 4 is the gas supply line 4 in the charge air housing 2 integrated and than over at least approximately the entire length of the internal combustion engine 1 extending bore 4 formed, which are below the Gaszuführventile 5 is arranged and supplies the same with gas. From the gas supply valves 5 each leads a tap hole 9 in the inlet channel 3 , The further arrangement corresponds to that according to 3 ,

In both embodiments, the mixture formation takes place, that is, the mixing of the through the Gaszuführventile 5 supplied gas with the housing over the charge air 2 supplied air, thus already partially in the intake ducts 3 , Both embodiments have in common is that the Gaszuführventile 5 in the charge air housing 2 are arranged. However, it would also be an arrangement of the same in the cylinder head 8th conceivable.

As the internal combustion engine 1 As mentioned above, six combustion chambers 7 have a total of six Gaszuführventile 5 intended.

Like again 1 can be removed is located in the charge air housing 2 a separating element 10 through which the charge air housing 2 in two chambers 2a and 2 B is divided. In other words, the charge air housing 2 is doubly formed. The separating element 10 is designed as a partition and extends into one as inflow 11 trained entrance area of the charge air housing 2 , which the separating element 10 also divided. In the entrance area into the charge air housing 2 are the chambers 2a and 2 B thus inflow channels 11a and 11b upstream. The inflow channels 11a and 11b are in this case designed such that a direct flow of the inlet channels 3 is prevented by the charge air.

The chambers 2a and 2 B have at least approximately the same volume, which ensures that the individual combustion chambers 7 during the intake stroke in each case the same air conditions To be available. The metering of the same amount of gas for each combustion chamber 7 take over the gas supply valves 5 by removing the gas from the common gas supply line 4 ,

The inflow of the charge air into the two chambers 2a and 2 B takes place here almost parallel to the longitudinal axis of the internal combustion engine 1 , whereby a direct flow of individual inlet channels 3 is avoided and an approximately equal filling of the combustion chambers 7 by approximately the same air conditions in the chambers 2a and 2 B is ensured.

The charge air housing 2 and the associated gas supply line 4 For example, they can be made of aluminum in the sand casting process and together form a modular component which, as in 3 and 4 represented, in a simple manner by screws 12 on the cylinder head 8th or on various cylinder heads 8th can be attached. In a manner not shown, electrical lines for controlling the Gaszuführventile 5 in the charge air housing 2 be integrated. The size of the charge air housing 2 allows a large charge air volume, resulting in a good and uniform filling of the combustion chambers 7 guaranteed.

In order to influence the mixture supply to the one of the chambers 2a respectively. 2 B associated combustion chambers 7 to prevent, are each of the chambers 2a respectively. 2 B only three combustion chambers each 7 assigned. The intake valves 6 are used to supply the gas-air mixture to the combustion chambers 7 only a maximum of 240 ° crank angle open long, with the open position of the intake valves 6 the gas-air mixture into the combustion chambers 7 flows. At a total crank angle of 720 ° per cycle of the engine 1 are thus only the inlet valves 6 a combustion chamber 7 per chamber 2a respectively. 2 B open and a vacuum for a particular combustion chamber 7 provided gas-air mixture through the other combustion chamber 7 supplied air flow is prevented. Generally, there should only ever be so many combustion chambers 7 one of the chambers 2a or 2 B be assigned to the firing distance of the chambers 2a respectively. 2 B associated combustion chambers 7 under the opening time of the intake valves 6 is, with respect to the opening time Ventilhubwege of less than 10% of Gesamtventilhubweg are not relevant.

In 2 is an internal combustion engine 1 with eight combustion chambers 7 shown in V-arrangement. Here, as in the embodiment according to 1 , one as a charge air line 13 designated line to in this case two charge air housings 2a and 2 B , In the charge air line 13 is also the separator 10 arranged and thus divides these into two lines 13a and 13b , As a result, an assignment of the two charge air housing 2a and 2 B to the two lines 13a and 13b given.

Alternatively, it would be in internal combustion engines 1 with combustion chambers 7 in V-arrangement also possible, only a common charge air housing 2 provide and perform this mehrflutig. The charge air housing 2 could then be one or more separators 10 have, which the charge air housing 2 in two or more chambers 2a . 2 B . 2c .... could split.

In an internal combustion engine 1 with four combustion chambers 7 could the charge air housing 2 also with the separating element 10 be provided and it could be any of the chambers 2a respectively. 2 B two combustion chambers 7 be assigned.

Due to the small number of combustion chambers 7 However, it would also be conceivable, no separating element 10 provide, since an influence due to the large ignition distance of 180 ° crank angle with a significant valve opening time of 180 ° -200 ° crank angle could be minimized by design measures.

As already mentioned above takes place in the inlet channel 3 the mixture formation by in the charge air housing 2 supplied charge air and that through the gas supply valve 5 in the inlet channel 3 introduced gas. To already before the introduction of the gas-air mixture in the combustion chamber 7 to achieve a certain mixing of gas and air, the gas supply valve 5 a certain time before the inlet valve 6 open and also closing the gas supply valve 5 occurs before closing the inlet valve 6 , Through this so-called pre-storage is the combustion chamber 7 initially only air, then a relatively rich gas-air mixture and finally again only air supplied. This guarantees that all the gas in the combustion chamber 7 and flushing losses of gas due to valve overlap do not occur.

To determine the thermodynamic state of the gas in the gas supply 4 are in the same a gas temperature sensor 14 and a gas pressure sensor 15 arranged for measuring gas temperature and gas pressure, the measured values of a control or regulating unit, not shown, of the internal combustion engine 1 can be supplied. Furthermore, there is a charge air sensor 16 provided for measuring the temperature and pressure of the charge air, which in this case in the chamber 2a angeord net is. These measurements are used to calculate and set the optimal combustion air ratio.

At the present, according to the Otto principle working internal combustion engine 1 the air mass flow is controlled by means of a throttle device, not shown. Depending on the operating condition of the internal combustion engine 1 This leads to more or less large throttle losses and thus to losses in terms of efficiency. In order to increase the efficiency of the air mass flow in the middle and high load range of the internal combustion engine 1 by means of the exhaust gas turbocharger already mentioned above, which has a variable turbine geometry regulated. The exhaust gas turbocharger here has to promote only that amount of air that the internal combustion engine 1 required so that the thermodynamic process more exhaust gas energy is available and no throttle losses occur through the throttle device.

Claims (8)

With a gaseous fuel powered, supercharged internal combustion engine ( 1 ), which have several combustion chambers ( 7 ), at least one line ( 13 ) and at least one housing ( 2 ) for supplying charge air to the combustion chambers ( 7 ), each combustion chamber ( 7 ) at least one inlet valve ( 6 ) and in addition to the at least one inlet valve ( 6 ) at least one with a gas supply line ( 4 ) connected gas supply valve ( 5 ) for supplying gas to a respective inlet channel ( 3 ), and wherein the at least one housing ( 2 ) or the at least one line ( 13 ) for supplying charge air through at least one fixed separating element ( 10 ) in at least two chambers ( 2a . 2 B ) with associated inflow channels ( 11a . 11b ) or in at least two lines ( 13a . 13b ) is divided. Internal combustion engine according to claim 1, characterized in that the inflow channels ( 11a . 11b ) are formed such that a direct flow of the inlet channels ( 3 ) is prevented by the charge air. Internal combustion engine according to claim 2, characterized in that the individual chambers ( 2a . 2 B ) each have at least approximately the same volume. Internal combustion engine according to one of claims 1, 2 or 3, characterized in that the at least one gas supply line ( 4 ) than in the housing ( 2 ) formed for supplying charge air bore is formed. Internal combustion engine according to one of claims 1, 2 or 3, characterized in that the at least one gas supply line ( 4 ) as separate to the housing ( 2 ) is arranged for supplying charge air arranged line. Internal combustion engine according to claim 4 or 5, characterized in that the gas supply line ( 4 ) together with the housing ( 2 ) forms a modular component for supplying charge air. Internal combustion engine according to one of claims 1 to 6, characterized in that the gas supply valves ( 5 ) within the housing ( 2 ) are arranged for the supply of charge air. Internal combustion engine according to one of claims 1 to 7, characterized in that those combustion chambers ( 7 ), which are ignited immediately one after the other, each with different chambers ( 2a respectively. 2 B ) assigned.